Why did the wartime alliance between the United States and the Soviet Union unravel?

A. The Soviet Union wanted a strong and united Germany.
B. The United States and the Soviet Union differed in their response to Nazi Germany.
C. The United States sought control over the satellite states.
D. The United States and the Soviet Union disagreed on the future of Eastern Europe.

D. The United States and the Soviet Union disagreed on the future of Eastern Europe. The Soviet Union wanted to create a buffer zone of friendly states in Eastern Europe to protect against future invasions, while the United States wanted to promote democracy and free markets in the region. This fundamental disagreement over the political and economic future of Eastern Europe led to tensions and eventual unraveling of the wartime alliance.